It’s no surprise that air quality tends to be worse in poor areas. But what happens when a country tries to reduce pollution? Do these efforts even out environmental inequalities, or do the rich reap more of the benefits?

Sadly, at least in the UK, the answer seems to be the latter. Researchers studied air quality improvements in Great Britain over a decade and found the biggest gains in affluent areas. Meanwhile, violations of environmental standards were increasingly borne by low-income neighborhoods.

Air pollution is a public health problem that has been linked to cardiovascular and respiratory disease. In previous analyses of Great Britain, researchers found that high nitrogen dioxide (NO2) levels in 2001 were disproportionately found in the poorest areas. “This is arguably the clearest ‘environmental injustice’ evidenced in the UK as air quality standards are intended to protect everyone,” the authors of the new study write in Environmental Research Letters.

The team took the investigation a step further and studied changes in air quality from 2001 to 2011 across Great Britain. The researchers also estimated the level of deprivation in each area, taking into account factors such as unemployment and lack of home and car ownership.

Overall, NO2 levels fell over the study period, thanks partly to new vehicle emissions standards. But the gap between the poor and rich widened. In 2001, NO2 levels were 40 percent higher in the poorest areas than in the richest areas; by 2011, that figure was 85 percent. The authors found a similar pattern for fine particulate matter. In 2001, levels in the poorest neighborhoods were about 10 percent higher than in the richest neighborhoods; a decade later, they were 14 percent higher.

The researchers also report a “very strong and steepening social gradient” for violations of NO2 standards. Among the areas that exceeded this pollution limit in 2001, nearly all of the affluent neighborhoods fixed the problem by 2011 — but only 70 percent of the poorest ones did. And new violations tended to appear in poor areas as well.

The results may not apply to other parts of the world. But the study is a sobering reminder that environmental improvements and environmental justice don’t always go hand in hand. — Roberta Kwok | 29 October 2015